This invention relates to telephone central office equipment and in particular, to a new and improved system for making cable transfers at the central office main frame and cable vault.
In a telephone central office, the subscribers line pairs come into a terminal area usually referred to as the cable vault. The line pairs are run from the terminals in the cable vault to terminals on the main frame by a cable, with electrical fault protection of subscribers being performed at the main frame. Maintenance and service functions are performed by telephone personnel at the cable vault and at the main frame, and one such operation is the transfer of line pairs from one location on the main frame via one cable to another location on the main frame via another cable. This operation is usually referred to as a cable transfer and may occur when a new cable is placed in service to supplement an existing cable.
A cable transfer operation typically is performed in the following manner. The old cable terminals for the line pair to be transferred are located at one part of the main frame. Temporary jumpers are run from these terminals to the new location cable terminals at the main frame to which this particular subscriber is to be connected. These jumpers are run across the face of the main frame, and the rest on the floor or in wire hangers. In the cable vault, the line pair in the new cable which is connected to these jumpered terminals is located, and then connected to the corresponding terminals of the old cable in the cable vault, after which the line pair of the old cable is removed. This operation is repeated for each line pair to be transferred. This requires the substantially continuous attention of a workman in the main frame area and a second workman in the cable vault. This also requires the running of jumpers across the main frame which is time consuming and hazardous and often inhibits work at the main frame.
In the past, a piece of switching equipment has been used in performing the cable transfer operation. A desk size console is installed in the central office and is connected by appropriate cables to the main frame, with plug in patch cords providing for connecting a plurality of line pairs from the main frame to the console. In one embodiment, provision is made for connecting up to 300 pairs at a time to the console. Typically 150 line pairs will be connected to a first cable and 150 line pairs will be connected to a second cable. The console has a plurality of switches which permit connecting each line pair to a jack. A workman at the console can select a first switch setting to connect a desired line pair of one cable to a corresponding jack and then select another switch setting to connect a line pair of the second cable to a corresponding jack, after which the line pairs can be interconnected by a patch cord inserted into the two selected jacks. This operation corresponds to the jumpering across the main frame previously discussed, after which the transfer is made by the second workman in the cable vault.
There are a number of disadvantages to this system. The console is large and requires substantially continuous attention by a workman. In order to produce the jumper connection, two switches must be actuated and a patch cord inserted.
It is an object of the present invention to provide a new and improved cable transfer system utilizing a small cable transfer panel at which the cable jumpering operation can be performed by actuation of a single switch. A further object is to provide such a cable transfer system wherein a plurality of line pairs can be jumpered at one time, with no further attention being required until the cable transfer has been completed for all of the lines so jumpered.
Additional objects include provision for interconnection of any line pairs by a patch cord, temporary and/or permanent connection of the cable transfer panel to the main frame and provision for connection of any group of line pairs of the main frame to the transfer panel, provision for connection of test equipment, and talk and tone circuits.
An additional object is to provide at one centralized location in a remote uncongested area of a central office, interconnection facilities as well as facilities for testing, taging, cross connecting, verifying and similar analytical operations.